Ammonia oxidizing apparatus



Feb. 21, 1933.

I. HECHENBLEIKNEB ET AL AMMONIA OXIDI Z ING APPARATUS Original Filed May18, 1927 2 Sheets-Sheet 1 INVENTORS l. HECHENBLEIKNER and N.T'ITLESTAD MA ORNEYS 1933- I. HECHENBLEIKNER ET AL 1,898,775

AMMONIA OXIDIZING APPARATUS 2 Sheets-Sheet 2 Original Filed May 18, 1927NITRIC OXIDES i TO ABSORPTION FEED OF AMMONIA LIQUOR AIR BLOWER WAT EREXIT INVENTORS I. HECHEN BLEIKNER and N. TITL STAD Patented Feb. 21,1933 UNITED STATES PATENT OFFICE INGENUIN HECHENBLEIKNER AND NICOLAYTITLESTAD, OF CHARLOTTE, NORTH CAROLINA, ASSIGNORS, BY MESNEASSIGNMENTS, TO CHEMICAL CONSTRUCTION CORPORATION, 01 CHARLOTTE, NORTHCAROLINA, A CORPORATION OF DELAWARE AMMONIA oxrnrzme APPARATUS Originalapplication filed May 18, 1927,

Serial N'o. 192,462, new Patent No. 1,748,646. Divided and thisapplication filed April 3, 1929. Serial No. 352,095.

This invention relates to the process and apparatus for the oxidation ofammonia; and this application is a division of our copending applicationfor ammonia oxidizing method and apparatus, Ser. No. 192.462, filed May18, 1927, now Patent 1,748,646 issued February 25, 1930.

As commonly practiced this process utilizes ammoniacal liquor as the rawmaterial. In essence the process consists in mixing ammonia in itsgaseous form with air or oxygen, as the case may be, and passing themixture through a catalytic converter, where after the process is oncestarted the ammonia interacts with the oxygen or with the oxygen in theair and is converted into oxides of nitrogen. This reaction isexothermic, generating a large amount of heat which is commonly utilizedfor preheating the mixture of the gaseous ammonia with the air or theoxygen before it reaches the converter.

In the process as commonly practiced however, the raw material utilizedis usually anammoniacal liquor. Before the conversion can take place theammoniais separated from the liquor by allowing the liquor to trickledownwardly through a stripping tower which is filled with small bodiesof solid inert material serving to divide the liquor into a plurality ofsmall streams. The air is blown into the stripping tower at the bottomthereof and traveling upward- 1y meets the streams of liquor and servesto drive off a substantial proportion of the ammonia dissolved in theliquor. In order, however, to attain a fairly complete separation of theammonia from the liquor it has been found necessary to heat the bottomof the stripping tower by various means thereby'in part preheating theair that enters the tower and in part directly heating the ammoniacalliquor at the bottom of the tower and assist in the separation of thegaseous ammonia from the liquor. Steam has been used for this purpose insufficient quantities for the evaporation of the ammonia and for heatingup the water and for compensating for heat losses.

It is very important that the steam or heat supply used in this processbe regulated properly for the reason that any excessive amount of heatwill evaporate the large stock of ammonia which is present in thestripping column and thereby cause the transmission of a very richgaseous mixture to the converter. This will result in a very intensereaction in the converter giving high combustion temperatures. As aresult of this, it frequently happens that the platinum gauze used as acatalizer in the converter burns out. This obviously causes aconsiderable amount of trouble in the replacement of the platinum gauzeas well as considerable expense.

Repeated efforts have been made to overcome these difficulties by theinstallation of automatically control-led steam valves and the like.This involves expensive and complicated installations which do notalways work reliably and which are always much too expensive andimpractical for small installations.

It is the object of the present invention to overcome the abovedifficulties in a very simple and inexpensive manner.

One of the objects of the present invention is to obviate the necessityof using any external source of heat for the vaporization of theammoniacal liquor or for the separation of the gaseous ammonia from itsmother liquor. In the present invention the heat ofthe exothermalreaction which takes place in the converter is utilized as a source ofheat for separation of the gaseous ammonia from the liquor.

Another object of the present invention is to make the two steps of theprocess above described, namely, the step of the separation of thegaseous ammonia from the mother liquor and the exothermal reaction,depend one upon the other in such a manner that the entire process isregulated automatically without any external devices or apparatus, theautomatic regulation being inherent in the process as described herein.

The above objects are accomplished broadly by causing the transfer ofsome of the heat generated in the converter to the stripping column orto the mother liquor with the result that the reaction heat causes theseparation of the gaseous ammonia from the ammoniacal liquor. In thismanner the use of an external source of heat for the vaporization of theammoniacal liquor is obviated thereby saving expense and apparatus, andin addition thereto the different parts of the process become sointerdependent and interrelated that each part thereof controls the rateof operation of the other parts thereof, and thus preventing thepossibility of the generation of an excessive amount of heat in theconverter which is likely to burn out the platinum gauze containedtherein.

While the process as discussed hereinabove and as more fully describedin later portions of this application is specifically applied to theoxidation of ammonia, the same process and apparatus may be applied toother processes in which an exothermal reaction takes place and ispreceded by the vaporization of the raw material.

The process and a paratus will be understood more clearly rom thedrawings and the description thereof which follows.

In the drawings, Fig. 1 illustrates one embodiment of the presentinvention,

Fig. 2 is a cross section on the lines 2-2 of Fig. 1, and

Fig. 3 shows another embodiment of the present invention.

In the drawings 10 indicates a storage tank of ammoniacal liquor, 11 isa level tank having a pipe 12 connecting the top thereof with the top ofthe storage tank 10. The pipe 12 serves to maintain a predeterminedlevel of ammoniacal liquor in the level tank 11. A pump 13 serves tofeed the liquor from the storage tank 10 into the top of the level tank11. A conduit 14 leads from a point near the bottom of the level tank 11to a point approximately near the middle of the stripping tower orvaporizing column 15. The conduit 14 is provided with an extension 16which projects into a vaporizing tower 15 and is additionally providedwith a valve 17 which may be adjusted to any desired rate of flow ofammoniacal liquor into the vaporizing column 15.

It should be noted at this point that the rate of operation of therocessdisclosed herein is controlled entire .y and solely by theadjustment of the valve 17. In prior processes the same valve 17 servedas a controlling element of the rate of operation of the system, but thesystem in addition thereto was subjected to possible variationsdependent upon the variations in the source of external heat employedfor heating the vaporizing column. By the present invention and by theprocess which constitutes an embodiment of the present invention anddisclosed herein this external source of variability is eliminated andthe only adjustment necessary is the adjustment of the valve 17. lViththe valve 17 once properly adjusted the various steps of the process andthe various parts of the apparatus serve as a check one upon the other,with the result that the process may then continue at a uniform rate.

The vaporizing tower 15 is provided with a foraminous false bottom 17which permits the passage of airtherethrough upwardly and the passage ofwaste liquor therethrough downwardly. The space above the false bottom17 is filled with small bodies of inert solids 18 to a point which fallssomewhat short of the top of the tower. The vaporizing tower 15 isprovided with a chamber 19 immediately below the foraminous bottom 17for the reception of the waste liquor 20 which is maintained at aconstant level by the waste overflow 21. An air blower 22 blows air intothe chamber 19 which passes upwardly in the column 15 and serves to aidin the vaporization of the mother liquor that trickles down in smallstreams on and between the solids 18. The tower 15 rests over the watertank 23 whose function and relation to the other parts of the a 'paratusand the process will be more fully escribed hereinafter.

The mixture of airand gaseous ammonia passes out of the vaporizing towerand downwardly by way of the pipe 24, and then upwardly by way of thepipe 25 shown in dotted lines in Fig. 1 where it is preheated by theproducts of combustion formed in the converter 26, and the mixture thenenters the converter 26 through a pipe 27. In the converter the gaseousammonia and the air are caused to interact to form oxides of nitrogen inthe presence of the catalyst, which may be a platinum gauze or any othersuitable catalyst. This reaction is accompanied by the generation ofheat so that the resultant products are heated. These products then passthrough the conduit 28 and enter the preheating chamber 29 whichsurrounds the pipe 25 and thereby transferring some of its heat to thegaseous mixture flowing therein. The reaction roducts then pass out ofthe system throug the conduit 30 and are directed to a Glover tower forthe absorption of the oxides of nitrogen.

Except for the water tank 23, the process and apparatus so far describedare old and well known in the art. The present invention is directed toa modification of the process whereby the use of any external heat forthe separation of the ammonia from the ammoniacal liquor is obviated.the heat being supplied by the reaction products formed in theconverter. For this purpose, the conduit 28 carrying the heated reactionproducts is surrounded by a water jacket 31 which in turn is put intocommunication with the water tank by means of the pipes 32 and 33, thepipe 32 connecting the upper portions of the tank 23 and the jacket31,whereas the pipe 33 connects the lower portions of the pipe 33 and thejacket 31.

The reaction products passing through the conduit 28 transfer their heatto the water in the jacket 31, and this hot water then-circulates inaccordance with the principle of the thermal siphon in the closed systemformed by the tank 23, the jacket 31 and the connecting pipes 32 and 33.

The water jacket 31 serves as a heater for the water tank 23 and willhereinafter be referred to as the water heater. This heater is given aheating surface whichis just sufficient to supply the heat required forthe separation of the gaseous ammonia from the amnioniacal liquor andalso supply the necessary concomitant heat losses. dimensions and designof the heater will depend upon the size of the installation and it maybe stated that in all cases the heater will reduce the temperature ofthe reaction products coming from the converter approximately 150 to 200C. 7

Assuming a constant flow of ammoniacal liquor into the vaporizing tower15 and a constant flow of air in the system, the rate of vaporization ofthe ammoniacal liquor, or rather, the rate of separation of gaseousammonia from the ammoniacal liquor will depend upon the temperature ofthe water tank 23, whichin turn depends'unon the temperature of theheater 31. On the other hand, the temperature of the reaction productsflowing through the conduit 28 which determine the temperature of theheater 31 itself depends upon the concentration of gaseous ammonia inthe mixture that passes into the converter 26. In this system,therefore, the process will continue uniformly and will depend entirelyupon the rate of flow of ammoniacal liquors in the vaporizing tower 15.Should it be desired at any time to increase the rate of operation ofthe process all that is necessary is toadjust the valve 17 to thedesired increased flow of ammoniacal liquors into the system. This willbring about a richer gaseous mixture entering the converter 26, causingthe generation of a larger amount of heat and an increased temperatureof the reaction products. This will cause the generation of a largeramount of heat, a rise to some extent in temperature, because of heatlosses being relatively less. and higher gas velocity through heater 31.This in creasehowever.of the amount of heat available for the separationof the gaseous ainmonia from the mother liquor will not be so large asto cause the sudden or rapid vaporization of the large store of ammoniawithin the vaporizing tower. In other words. the process disclosedherein is inherently and automaticallv self regulating without theapplication of any external source of heat or any external device of anykind.

The specific Fig. 3 shows a modification-of the process and apparatusdisclosed in Fig. 1. For the purpose of comparison and for the purposeof making this figure readily intelligible,

reference numerals which are related to the reference numerals shown inFig. 1 by the addition of the digit 3 thereto will be used forindicating similar vparts.

In Fig. 3, 153 indicates the stripping or vaporizing column whichreceives its ammonical liquor through the conduit 143. The mixture ofgaseous ammonia and air passes through the conduit 243 and through thefilter 40, and then through the conduit 253 shown in dotted lines whichis surrounded by the preheater 293, and thenalong the conduit 273 intothe converter 263. The reaction products pass through the conduit 283transferring some of their heat to the water heater 313 and then throughthe preheater 293 and out through the conduit 303 to-the absorptiontower not shown. As in the apparatus and process, shown in Fig. 1, theheater 313 communicates with the water tank 233 by means of the pipes323 and 333. In this modification of the invention, however, the tank233 is open at the top and serves to receive the waste liquor which ispractically denuded of its ammonia contents. The hot water in the tank233 is maintained at a predetermined level by means of the overflow pipe41, the heat overflow passing through the coil 42- and is dischargedthrough the outlet- 43. The coil 42 is surrounded by a chamber 44 andthe air blower 223.communicates with the bottom of the said chamber. Theair is therefore preheated in the chamber 44 and passes through conduit45 into the bottom of the stripping orvaporizing column 153 at the pointimmediately over the level of the hot water and waste liquor in the tank233. The stripping or vaporizing tower 153 is additionally provided witha cooler 46 which may be so constructed as to surround the tower at thetop thereof or in similar installations it may be enclosed inside thetower. The cooler 46 serves to condense any water vapor that may pass upthe column and thus prevents the entry of any water vapor into theconverter 263.

The principle of operation of the process and apparatus shown in Fig. 3is the same as that shown in Fig. 1. The heat necessary for theseparation of the gaseous ammonia from thdammoniafliiquor is derivedentirely from the heat reaction products with the same advantageousresults as those described before. The rate of the reaction will dependentirely upon the rate of feeding of the ammonia liquor. The heater 313is so designed as to supply the necessary amount of heat for thatpurpose and also to supply the heat losses of the system. The process,like the process described in connection with Figl is inherentlyautomatically regulated to maintain a uniform rate of reaction withinthe converter and thus obviating the possibilities of burning out theplatinum gauze. In addition to these advantages in the process andapparatus shown in Fig. 3, the air entering the vaporizing column ispreheated and the cooler or condenser 46 serves to prevent the increaseof water vapor into the converter.

The process and apparatus shown in Fig. 3, like that shown in Fig. 1,may, if desired, be applied to processes other than the oxidation ofammonia in which an exothermal reaction takes place which is preceded bythe vaporization of the raw material.

It should also be noted that in the process shown in Fig. 3 the heatexchanger 293 works on the counter-current principle which makes itpossible to utilize almost all of the heat generated in the converter263, part of the heat being transferred to the vaporizing tower andutilized for theseparation of the ammoniacal gas from the mother liquor,and the remainder of the heat being utilized for preheating'the gaseousmixture before it enters the converter 263.

This system as shown in either Figs. 1 or 3, is very flexible and willnot require any attention. There are no complicated valves or mechanismto watch, which is of special advantage in small plants. There can be nofear of excessive heat in the system, as the quantity is limited by theheat of reaction at the capacity of the plant and the heating surface ofthe heater. There can be no sudden changes in heat because of thelimited. quantity of heat at disposal.

In case of operation of the plant at lower than rated capacity, therewill theoretically be an excess of heat, because the heating surface ofthe heater is then comparatively larger. The heat losses of the plantwill, however, fully or partly take care of this. The temperature of gasentering the heater will be less, the flow slower, which reduces theheat transmission approximately by the square root of the velocity, andthe heat loss of the stripping column relatively higher. All taken intoconsideration there will. by correct design. be approximately constantconditions at all rates of flow. The

small fluctuations and irregularities that may occur will be taken care.of by the cooler at the top of the stripping column.

It will also be apparent that while we have shown and described ourinvention in the preferred form, many changes and modifications may bemade in the structure disclosed without departing from the spirit of theinvention, defined in the following claims.

lVe claim:

1. In an apparatus for the oxidation of ammonia comprising a vaporizingtower, catalytic converter, means associated with said catalyticconverter adapted to be heated by the reaction heat generated in saidconverter, and a heater for said vaporizing tower connected to saidmeans and deriving its heat therefrom.

2. In an apparatus for the oxidation of ammonia comprising a vaporizingcolumn, a catalytic converter, and means for transferring reaction heatfrom the catalytic converter to the vaporizing column including a watercontaining heater in said vaporizing column connected-to said converterand. deriving its heat from the reaction products of said converter.

3. In an apparatus for the oxidation of ammonia comprising a vaporizingcolumn, a

catalytic converter, a conduit leading from the converter and carryingthe reaction products, and heater means for transferring reaction heatfrom said converter to the vaporizing column including a water jacketsurrounding said conduit.

4. In an apparatus for .the oxidation of ammonia comprising a vaporizingcolumn, a catalytic converter, and means for transferring reaction heatfrom the catalytic converter to the vaporizing column comprising a watertank disposed below said vaporizing column and a heater in communicationtherewith deriving its heat from the reaction products of the converter5. In an apparatus of the oxidation of ammonia comprising a vaporizingcolumn, a catalytic converter, a conduit carrying reaction products fromsaid converter, and means for transferring reaction heat to thevaporizing column including a water heater surrounding said conduit anda water tank disposed below said vaporizingcolumn and in communicationwith said heater.

6. An apparatus for the oxidation of ammonia comprising a vaporizingcolumn, a catalytic converter, a conduit leading the reaction productsfrom said converter, a water heater associated with said conduit toderive its heat from said reaction products, a water tank disposed atthe bottom of the vaporizing column in communication with said waterheater, overflow means for said water tank, a chamber surrounding saidoverflow means in communication with said vaporizing column, and meansfor blowing air into said vaporizing column connected to said chamber. 7

7. In an apparatus for subjecting a material to vaporization and to anexothermic reaction. a vaporizing chamber for subjecting the material tovaporization, a reaction chamber for subjecting the vaporized materialto an exothermic reaction, and means for transferring the reaction heatfrom the reaction chamber to the vaporizing chamber for vaporizationpurposes, said means comprising a heater for said vaporizing chamber, aheat exchange means for said reaction chamber, and means connecting theheater to said heat exchange means.

8. I11 an apparatus for separating a gas from a liquor containing saidgas and for subjecting said gas to an exothermic reaction comprising achamber for separating the gas from the liquor, means for mixing airwith said gas, a reaction chamber for subjecting said mixture to anexothermic reaction, means associated with said reaction chamber adaptedto be heated by the reaction heat generated therein, and a heater forsaid separating chamber connected to said means and deriving its heattherefrom.

9. In an apparatus for the oxidation of ammonia comprising a vaporizingtower, a catalytic converter, a first heat exchange means connectingsaid catalytic converter with said vaporizing tower for preheating thegases moving from the vaporizing tower to the catalytic converter, and asecond heat -exchange means connecting said vaporizing tower with thecatalytic converter for transferring reaction heat from the converter tothe vaporizing tower to vaporize the ammonia therein.

10. In an apparatus for the oxidation of ammonia comprising a vaporizingtower, a catalytic converter, heat exchange means connecting thevaporizing tower with the catalytic converter and operative fortransferring reaction heat from the catalytic converter to thevaporizing tower to vaporize the ammonia therein, means forintroducingair into the vaporizing tower for mixture with the vaporizedgases therein, and means for utilizing a portion of the heat of saidheat exchange means for preheating the air introduced into the saidvaporing tower.

11. In an apparatus for the oxidation of ammonia comprising a vaporizingtower, a catalytic converter, heat exchange means connecting thevaporizing tower with the catalytic converter and operative fortransferring reaction heat from the catalytic converter to thevaporizing tower to vaporize the ammonia therein, means for introducingair into the vaporizing tower for mixture with the vaporized gasestherein, means for utilizing aportion of the heat ofs'ai'd heat exchangemeans for preheating the air introduced into the said vaporizing tower,and a second heat exchange means connecting the converter with thevaporizing tower for preheating the mixture of gases moving from thevaporizing tower to the converter.

12. In an apparatus for the oxidation of ammonia comprising a vaporizingtower, a

catalytic converter, a heat exchange means connecting the vaporizingtower. with the catalytic converter including "a water circulatingsystem and operative for transferring reaction heat from the catalyticconverter to the vaporizing tower tovaporize the ammonia therein, meansfor blowing air into the vaporizing tower for mixture with the vaporizedgases therein, means for utilizing a portion of the heat of said watercirculating system for preheating the air introduced into the saidseparating tower, and a second heat exchange means connecting theconverter with the vaporizing tower for preheating the mixture of gasesmoving from the vaporizing tower to the converter. 13. In an apparatusfor the oxidation of ammonia comprising a vaporizing tower, a catalyticconverter, heat exchange means connecting the vaporizing tower with thecatalytic converter including a water circulating system and operativefor transferring reaction heat from the catalytic converter to thevaporizing tower to vaporize the ammonia therein, means for blowing airinto the vaporizing tower for mixture with the vaporized gases therein,and means for utilizing a portion of the heat of said water circulatingsystem for preheating the air introduced into the said vaporizing tower.

14. In an apparatus for theoxidation of ammonia comprising a vaporizingtower, a catalytic converter, an exit conduit for said converter, afirst heat exchange means connecting said exit conduit with saidvaporizing tower for preheating the gases moving from the vaporizingtower to the catalytic converter, and a second heat exchange'meansconnecting said vaporizing tower with said exit conduit for transferringreaction heat from the converter to the vaporizing tower to vaporize theammonia therein.

15. In an apparatus for-separating a gas from a liquor containing saidgas and for subjecting said gas to an exothermic reaction comprising achamber for separating the gases from the liquor, means'for' mixing airwith said gas, a reaction chamber for subjecting said mixture to anexothermic reaction, and a water circulating system for transferringheat from the reaction chamber to the gas separating chamber forseparating the gas from the liquor therein.

Signed by said INGENUIN' HECIIENBLEIK- NIIR at Charlotte in the countyof Mecklenburg and State of North Carolina this 25 day of March A. D.1929. I

INGENUIN HECHENBLEIKNER.

Signed by said N ICOLAY TITLESTAD at Bnflalo, in the county of Erie andState of New York, this 29 day of March, 1929.

N ICOLAYTEITLESTAD

